Insulation boards and methods for their manufacture

ABSTRACT

A method for producing polyisocyanurate insulation foams, the method comprising contacting an A-side stream of reactants that includes an isocyanate with a B-side stream of reactants that include a polyol and a blowing agent, where the blowing agent includes isopentane and n-pentane in a substantial absence of cyclopentane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of pending U.S. patentapplication Ser. No. 10/640,895, filed Aug. 13, 2003, which claims thebenefit of U.S. Provisional Patent Application No. 60/403,325, filed onAug. 13, 2002.

FIELD OF THE INVENTION

This invention relates to the manufacture of polyisocyanurate insulationboards and more particularly toward the use of a certain blowing agentmixture.

BACKGROUND OF THE INVENTION

Polyurethane and polyisocyanurate foam insulation boards are commonlyemployed in the construction industry. These insulation boards arecellular in nature and typically include an insulating compound trappedwithin the cells of the foam. For example, it is common to produceinsulation boards by employing hydrochlorofluorocarbons as a blowingagent, which thereby entraps these compounds within the cell network forpurposes of improving the insulating ability of the foam.

Because fluorinated and chlorinated carbon compounds, such ashydrochlorofluorocarbons, may have a deleterious impact on theenvironment, many governments have or will prohibit the use of thesecompounds in the manufacture of foam. Many alternative blowing agentshave been proposed including the use of certain hydrocarbons. Inparticular, pentane and isomers of pentane have been employed as blowingagents with a relative degree of commercial success. For example, blendsincluding cyclopentane together with isopentane are commonly employed asa substitute for halogenated carbon compounds.

The presence of the cyclopentane has advantageously provided usefulshort-term insulation values (i.e., R values). Cyclopentane, however, isexpensive. Also, cyclopentane is believed to partially solubilizepolyurethane and polyisocyanurate polymers, and therefore its presencewithin the cells of the insulation board may deleteriously impactdimensional stability or deleteriously impact long-term R values.Furthermore, this ability to solubilize the foam material ultimatelyleads to poorer or higher diffusion rates which has a deleterious effecton long-term R values.

There is therefore a need to improve upon the hydrocarbon-based blowingagent systems currently employed in the manufacture of foams,particularly polyisocyanurate foams.

SUMMARY OF THE INVENTION

In general the present invention provides a method for producingpolyisocyanurate insulation foams, the method comprising contacting anA-side stream of reactants that includes an isocyanate with a B-sidestream of reactants that include a polyol and a blowing agent, where theblowing agent includes isopentane and n-pentane in a substantial absenceof cyclopentane.

The present invention also includes a method for producingpolyisocyanurate insulation foams, the method comprising contacting anisocyanate-reactive compound with an isocyanate compound in the presenceof a blowing agent that includes both isopentane and n-pentane in thesubstantial absence of cyclopentane, where the isopentane is present ina weight fraction that is greater than the weight fraction of then-pentane.

The present invention further includes a method for producingpolyisocyanurate insulation foams, the method comprising contacting anA-side stream of reactants that includes an isocyanate with a B-sidestream of reactants that include a polyol and a blowing agent, where theblowing agent includes isopentane and n-pentane in a substantial absenceof cyclopentane, where the weight ratio of the isopentane to then-pentane if from 7:1 to 1:1.

By employing a blowing agent system that includes isopentane andn-pentane in the substantial absence of cyclopentane, the presentinvention overcomes many of the problems associated with the prior artand allows for the economic and efficient manufacture of technologicallyuseful insulation boards. To begin with, the preferred embodiments donot employ chlorinated or fluorinated carbon compounds. And, while theprocess employs hydrocarbon blowing agents, the substantial absence ofcyclopentane provides for insulation boards that are not as susceptibleto dimensional instability concerns that may by caused by cyclopentane.Moreover, the use of a blend of isopentane and n-pentane hassurprisingly provided insulation boards with useful insulatingefficiency despite the substantial absence of cyclopentane.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The manufacture of polyisocyanurate or polyurethane insulation boardsaccording to the present invention employs a blowing agent system thatincludes isopentane and n-pentane in the substantial absence ofcyclopentane.

In general, and in a manner that is conventional in the art, theinsulation boards of the present invention are produced by developing apolyurethane and/or polyisocyanurate foam in the presence of a blowingagent. The foam is preferably prepared by contacting an A-side stream ofreagents with a B-side stream of reagents and depositing the mixture ordeveloping foam onto a laminator. As is conventional in the art, theA-side stream includes an isocyanate and the B-side includes anisocyanate-reactive compound.

The A-side stream typically only contains the isocyanate, but, inaddition to isocyanate components, the A-side stream may containflame-retardants, surfactants, blowing agents and othernon-isocyanate-reactive components.

Suitable isocyanates are generally known in the art. Useful isocyanatesinclude aromatic polyisocyanates such as diphenyl methane, diisocyanatein the form of its 2,4′-, 2,2′-, and 4,4′-isomers and mixtures thereof,the mixtures of diphenyl methane diisocyanates (MDI) and oligomersthereof known in the art as “crude” or polymeric MDI having anisocyanate functionality of greater than 2, toluene diisocyanate in theform of its 2,4′ and 2,6′-isomers and mixtures thereof, 1,5-naphthalenediisocyanate, and 1,4′diisocyanatobenzene. Preferred isocyanatecomponents include polymeric Rubinate 1850 (Huntsmen Polyurethanes),polymeric Lupranate M70R, and polymeric Mondur 489N (Bayer).

The B-side stream, which contains isocyanate reactive compounds, mayalso include flame retardants, catalysts, emulsifiers/solubilizers,surfactants, blowing agents fillers, fungicides, anti-static substances,water and other ingredients that are conventional in the art.

The preferred isocyanate-reactive component is a polyol. The termspolyol or polyol component include diols, polyols, and glycols, whichmay contain water as generally known in the art. Primary and secondaryamines are suitable, as are polyether polyols and polyester polyols.Useful polyester polyols include phthalic anhydride based PS-2352(Stepen), phthalic anhydride based polyol PS-2412 (Stepen), teraphthalicbased polyol 3522 (Kosa), and a blended polyol TR 564 (Oxid). Usefulpolyether polyols include those based on sucrose, glycerin, and toluenediamine. Examples of glycols include diethylene glycol, dipropyleneglycol, and ethylene glycol. Of these, a particularly preferred glycolis diethylene glycol. Suitable primary and secondary amines include,without limitation, ethylene diamine, and diethanolamine. The preferredpolyol is a polyester polyol, and the present invention is preferablypracticed in the appreciable absence of any polyether polyol. Mostpreferably, the ingredients are devoid of polyether polyols.

Catalysts are believed to initiate the polymerization reaction betweenthe isocyanate and the polyol, as well as a trimerization reactionbetween free isocyanate groups when polyisocyanurate foam is desired.While some catalysts expedite both reactions, it is common to employ twoor more catalysts to achieve both reactions. Useful catalysts includesalts of alkali metals and carboxylic acids or phenols, such as, forexample potassium octoate; mononuclear or polynuclear Mannich bases ofcondensable phenols, oxo-compounds, and secondary amines, which areoptionally substituted with alkyl groups, aryl groups, or aralkylgroups; tertiary amines, such as pentamethyldiethylene triamine(PMDETA), 2,4,6-tris[(dimethylamino)methyl]phenol, triethyl amine,tributyl amine, N-methyl morpholine, and N-ethyl morpholine; basicnitrogen compounds, such as tetra alkyl ammonium hydroxides, alkalimetal hydroxides, alkali metal phenolates, and alkali metal acholates;and organic metal compounds, such as tin(II)-salts of carboxylic acids,tin(IV)-compounds, and organo lead compounds, such as lead naphthenateand lead octoate.

Surfactants, emulsifiers, and/or solubilizers may also be employed inthe production of polyurethane and polyisocyanurate foams in order toincrease the compatibility of the blowing agents with the isocyanate andpolyol components.

Surfactants serve two purposes. First, they help to emulsify/solubilizeall the components so that they react completely. Second, they promotecell nucleation and cell stabilization. Typically, the surfactants aresilicone co-polymers or organic polymers bonded to a silicone polymer.Although surfactants can serve both functions, a more cost effectivemethod to ensure emulsification/solubilization is to use enoughemulsifiers/solubilizers to maintain emulsification/solubilization and aminimal amount of the surfactant to obtain good cell nucleation and cellstabilization. Examples of surfactants include Pelron surfactant 9868A,Goldschmidt surfactant B8469, and CK-Witco's L 6912. U.S. Pat. Nos.5,686,499 and 5,837,742 are incorporated herein by reference to showvarious useful surfactants.

Suitable emulsifiers/solubilizers include DABCO Kitane 20AS (AirProducts), and Tergitol NP-9 (nonylphenol+9 moles ethylene oxide).

Flame Retardants are commonly used in the production of polyurethane andpolyisocyanurate foams, especially when the foams contain flammableblowing agents such as pentane isomers. Useful flame retardants includetri(monochloropropyl) phosphate, tri-2-chloroethyl phosphate, phosphonicacid, methyl ester, dimethyl ester, and diethyl ester. U.S. Pat. No.5,182,309 is incorporated herein by reference to show useful blowingagents.

The blowing agents employed in practicing this invention include a blendof isopentane and n-pentane in the substantial absence of cyclopentane.In addition to isopentane and n-pentane, the blowing agent mayoptionally include other blowing agents such as alkanes, (cyclo)alkanes,hydrofluorocarbons, hydrochlorofluorocarbons, fluorocarbons, fluorinatedethers, alkenes, alkynes, carbon dioxide, and noble gases.

Suitable alkanes and (cyclo)alkanes include neopentane, n-butane,cyclobutane, methylcyclobutane, isobutane, propane, cyclopropane,methylcyclopropane, n-hexane, 3-methylpentane, 2-methylpentane,cyclohexane, methylcyclopentane, n-heptane, 2-methylheptane,3-ethylpentane, 2,2,3-trimethylbutane, 2,2-dimethylpentane,cycloheptane, methylcyclohexane and 2,3-dimethylbutane.

Suitable hydrofluorocarbons include 1,1,1,2-tetrafluoroethane (HFC134a), 1,1,1,4,4,4hexafluorobutane (HFC 356), pentafluoroethane (HFC125), 1,1-difluoroethane (HFC 152a), trifluoromethane (HFC 23),difluoromethane (HFC 32), trifluoroethane (HFC 143) and1,1,1,3,3-pentafluoropropane (HFC 245FA), fluoromethane.

Suitable hydrochlorofluorocarbons include chlorodifluoromethane (HCFC22), 1-chloro-1,1-difluoroethane (HCFC 142b),1,1,1-trifluoro-2,2-dichloroethane (HCFC 123) and dichlorofluoromethane(HCFC 21).

Suitable fluorocarbons include perfluoromethane (R14),perfluorocyclobutane, perfluorobutane, perfluoroethane andperfluoropropane.

Suitable fluorinated ethers include bis-(trifluoromethyl)ether,trifluoromethyl difluoromethyl ether, methyl fluoromethyl ether, methyltrifluoromethyl ether, bis(difluoromethyl)ether, fluoromethyldifluoromethyl ether, methyl difluoromethyl ether,bis-(fluoromethyl)ether, 2,2,2-trifluoroethyl difluoromethyl ether,pentafluoroethyl trifluoromethyl ether, pentafluoroethyl difluoromethylether, 1,1,2,2-tetrafluoroethyl difluoromethyl ether,1,2,2,2-tetrafluoroethyl fluoromethyl ether, 1,2,2-trifluoroethyldifluoromethyl ether, 1,1-difluoroethyl methyl ether and1,1,1,3,3,3-hexafluoroprop-2-yl fluoromethyl ether.

Suitable noble gases include krypton, argon and xenon. Preferred blowingagents include those having zero ozone depletion potential.

While other blowing agents may also be added, it is preferred that theblowing agent mixture is devoid of halogenated blowing agents, and it isespecially preferred that the blowing agent mixture is essentiallydevoid of hydrofluorocarbons and hydrochlorofluorocarbons.

With respect to the amount of isopentane to n-pentane, it is preferredto employ an isopentane to n-pentane weight ratio of 9:1 to about 1:2,more preferably from 7:1 to 1:1, more preferably from about 5:1 to1.5:1, even more preferably from about 4:1 to 1.7:1, still morepreferably 3:1 to about 3:1, and even more preferably 2.7:1 to about2.3:1. Preferably, the blend includes a greater weight fraction ofisopentane. While other blowing agents can be employed, it is preferredthat the blowing agents comprise at least 90% weight of the mixture ofisopentane and n-pentane, and even more preferably at least about 95% ofthe mixture of isopentane and n-pentane.

In order to achieve the benefits of this invention, there should be asubstantial absence of cyclopentane. In other words, the ingredients,especially the blowing agents, should not contain more than aninsubstantial amount of cyclopentane. The terms substantial absence orinsubstantial amount refer to that amount (or less) of cyclopentane thatwill not have an appreciable impact on the characteristics of theblowing agent mixture or the polyisocyanurate insulation boards. Forexample, it is known that a threshold amount of cyclopentane will impactthe dimensional stability of the polyisocyanurate insulation boards.That amount of cyclopentane that will not impact the characteristics ofthe polyisocyanurate insulations boards is an insubstantial amount ofcyclopentane.

In a preferred embodiment, the ingredients, especially the blowingagents, will include only trace amounts or less of cyclopentane. Morepreferably, the blowing agent mixture may only include less than 1.0weight % cyclopentane, more preferably less than 0.5 weight %cyclopentane, and even more preferably less than 0.1 weight %cyclopentane.

Practice of the present invention generally does not alter the amount ofany ingredient employed or the relative ratios of any of theingredients. In general, an excess of isocyanate to polyol is employed,especially where an isocyanurate foam is desired. For example, where apolymeric isocyanate is employed as the A-side reactant, about 150 toabout 300 parts by weight of polymeric isocyanate per 100 parts byweight of polyol is employed (php).

The blowing agent mixture, which includes the mixture of isopentane andn-pentane, as well as any additional blowing agents that may beemployed, should be employed in an amount from about 10 to about 40parts by weight blowing agent php, and even more preferably in an amountfrom about 15 to about 35 parts by weight blowing agent php.

With regard to the other ingredients, it is preferred to employ fromabout 0.5 to about 6 parts by weight surfactant php, from about 0.1 toabout 2 parts by weight water php and from about 0 to about 25 parts byweight flame retardant php. The amount of catalyst employed may varygreatly depending on the type or nature of the catalyst, but it istypically common to employ from about 1 to about 7 parts by weight metalsalt php and about 0.1 to about 3 parts by weight amine php.

Besides employing the mixture of isopentane and n-pentane in thesubstantial absence of cyclopentane, practice of this invention does notnecessarily alter the procedures employed in preparing foam insulationboards.

For example, the process employed may include conventional low pressuremixing whereby the B-side reactants and blowing agent are mixed underatmospheric pressure and at temperatures of about 18° C. to about 29° C.The B-side mixture is then delivered to a mix head at a temperature ofabout 18° C. to about 29° C. and a pressure of about 25 psi to about 200psi. The A-side stream is likewise delivered to the same mix head at atemperature of about 18° C. to about 38° C. and a pressure of about 25psi to about 200 psi. The A-side and B-side reactants undergo mixing atthis mix head and the resulting mixture becomes a developing foam thatis deposited onto a laminator. The laminator may include a facermaterial onto which the developing foam is deposited. A second facermaterial may optionally be applied to the upper surface of thedeveloping foam. The ultimate size of the resultant foam board ismanipulated by adjusting the height of the moving form, i.e., restrainedrise, by adjusting the sides of the moving form to a desired width, andby cutting the continuous foam product to a desired length.

In a preferred embodiment, the process includes high pressure mixingwhereby the B-side reactants and blowing agents are mixed within adynamic pin mixer at pressures in excess of about 80 psi at temperaturesin excess of 10° C. This particular procedure is disclosed in aco-pending international patent that designates the United States(PCT/US02/06823), which is incorporated herein by reference. Aftermixing at the pin mixer, the B-side reactants are heated to atemperature of about 16° C. to about 29° C., and the pressure isincreased to a pressure of about 1,800 to about 2,400 psi prior todelivery to the mix head where the temperature increases to about 27° C.to about 35° C.

The A-side is fed to the mix head at a temperature of about 29° C. toabout 35° C. and a pressure of about 1,800 to about 2,400 psi. Aftermixing at the mix head, the developing foam is likewise deposited onto alaminator.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

1. A method for producing polyisocyanurate insulation foams havingdimensional stability, the method comprising: providing a blowing agentincluding isopentane and n-pentane in a substantial absence ofcyclopentane, and having an isopentane to n-pentane weight ratio of from2.7:1 to 1:1; first combining and pressurizing a B-side stream ofreactants, including a polyol and the blowing agent, under a pressure inexcess of about 80 psi and at a temperature in excess of about 10° C.;and then contacting an A-side stream of reactants that includes anisocyanate with the B-side stream of reactants.
 2. The method of claim1, where said step of combining includes combining said polyol and saidblowing agent within a dynamic pin mixer.
 3. The method of claim 1,where said step of contacting occurs within a mix head, where the B-sidestream of reactants are at a temperature of about 29° C. to about 35° C.and a pressure of about 1,800 to about 2,400 psi, and where said A-sidestream of reactants is at a temperature of about 29° C. to about 35° C.and a pressure of about 1,800 to about 2,400 psi.
 4. The method of claim1, where the blowing agent includes at least about 90% by weight of themixture of isopentane and n-pentane.
 5. The method of claim 1, where theblowing agent consists essentially of isopentane, n-pentane, andoptionally at least one other blowing agent having a zero ozonedepletion potential.
 6. The method of claim 1, where the amount ofblowing agent employed is from about 10 to about 40 parts by weightblowing agent per 100 parts by weight polyol.
 7. The method of claim 1,where the polyol is preblended with at least one of a surfactant, water,a flame retardant, or a catalyst prior to contacting the polyol with theisocyanate compound.
 8. The method of claim 1, where the step ofcontacting mixes the A-side and B-side streams of reactants to form amixture of polyisocyanurate ingredients, and further comprisingdepositing the mixture of polyisocyanurate ingredients onto a laminatorand allowing the mixture of polyisocyanurate ingredients to form adeveloping foam.
 9. A method for producing polyisocyanurate insulationfoams, the method comprising: high pressure mixing of a B-side stream ofreactants, including a polyol and a blowing agent, under a pressure inexcess of about 80 psi and at a temperature in excess of about 10° C.,wherein the blowing agent agent includes isopentane and n-pentane in asubstantial absence of cyclopentane, and wherein the blowing agent hasan isopentane to n-pentane weight ratio of from 2.7:1 to 1:1; and thencontacting an A-side stream of reactants that includes an isocyanatewith the B-side stream of reactants.
 10. The method of claim 9, wherethe B-side stream of reactants further includes water in an amount fromabout 0.1 to about 2.0 parts by weight per 100 parts polyol.
 11. Themethod of claim 9, where said step of contacting occurs within a mixhead, where the B-side stream of reactants are at a temperature of about29° C. to about 35° C. and a pressure of about 1,800 to about 2,400 psi,and where said A-side stream of reactants is at a temperature of about29° C. to about 35° C. and a pressure of about 1,800 to about 2,400 psi.12. The method of claim 9, where the blowing agent includes less than1.0 weight % cyclopentane.
 13. The method of claim 9, where the blowingagent includes less than 0.5 weight % cyclopentane.
 14. The method ofclaim 9, where the step of contacting mixes the A-side and B-sidestreams of reactants to form a mixture of polyisocyanurate ingredients,and further comprising depositing the mixture of polyisocyanurateingredients onto a laminator and allowing the mixture ofpolyisocyanurate ingredients to form a developing foam.